Climate change is the long-term shift in average weather patterns across the world. Since the mid-1800s, humans have contributed to the release of carbon dioxide and other greenhouse gases into the air. This causes global temperatures to rise, resulting in long-term changes to the climate.4 Below is an explanation of climate change from the US National Aeronautics and Space Administration (NASA) and artistic interpretations of climate change from the artist Jill Pelto.

NASA:

The Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 11,700 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.

The current warming trend is of particular significance because most of it is extremely likely (more than a 95 percent probability) to be the result of human activity since the mid-20th century and it is proceeding at a rate that is unprecedented. Scientists attribute the global warming trend observed since the mid-20th century to the human expansion of the greenhouse effect, a warming that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere block heat from escaping. Long-lived gases that remain semi-permanently in the atmosphere and do not respond physically or chemically to changes in temperature are described as forcing climate change.

Climate change encompasses global warming but refers to the broader range of changes that are happening to our planet. These include rising sea levels; shrinking mountain glaciers; accelerating ice melt in Greenland, Antarctica, and the Arctic; and shifts in flower and plant blooming times. These are all consequences of the warming, which is caused mainly by people burning fossil fuels and putting out heat-trapping gases into the air. The terms global warming and climate change are sometimes used interchangeably, but strictly they refer to slightly different things.⁵ 

⁵ NASA, ‘Climate Change: How Do We Know?’, NASA Global Climate Change - Vital Signs of the Planet, accessed 14 October 2021, https://climate.nasa.gov/evidence/ 

Jill Pelto

Dwindling Migration uses data that documents the dramatic decline in caribou population herds, focusing on the George River Caribou Herd from 1980 to the present day. Unfortunately, this trend is seen in most caribou herds globally.⁶ 

⁶Jill Pelto, Dwindling Migration, 2016, 2016, https://www.jillpelto.com/caribou

Figure 2: Dwindling Migration, Watercolor and Pencil (2016)

The Intergovernmental Panel on Climate Change (IPCC) Special Report on Global Warming highlights climate impacts at the current ~1°C global warming as well as the risks of reaching a 1.5°C and the irreversible losses that would take place should global warming reach 2°C or more. 

We need political leadership to immediately cut emissions across all sectors of the economy, in order to limit warming to 1.5°C. Global warming is likely to be the greatest cause of species extinctions this century. The IPCC says a 1.5°C average rise may put 20-30% of species at risk of extinction. If the planet warms by more than 2°C, most ecosystems will struggle. Many of the world’s threatened species live in areas that will be severely affected by climate change. And climate change is happening too quickly for many species to adapt.⁹ 

Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted, and trees are flowering sooner. Effects that scientists had predicted in the past would result from global climate change are now occurring: loss of sea ice, accelerated sea level rise and longer, more intense heat waves.

Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gases produced by human activities. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century.

According to the IPCC, the extent of climate change effects on individual regions will vary over time and with the ability of different societal and environmental systems to mitigate or adapt to change.¹⁰ 

Global effects of climate change include:

• Global Temperature Rise

• Warming Oceans

• Shrinking Ice Sheets

• Glacial Retreat

• Decreased Snow Cover

• Sea Level Rise

• Declining Artic Sea Ice

• Extreme Weather

• Change in precipitation patterns

• More Droughts and Heat Waves

• Ocean Acidification

• Mass Migration

• Species Extinction

Resources on impact of climate change: